 | | Report (volume) | | GEOLOGY OF THE IGNEOUS ROCKS OF THE HIGHWOOD MOUNTAINS, MONTANA BY LOUIS VALENTINE PIRSSO1ST WASHINGTON........................................... -----Highwood Peak stock....-.-.-..........-._.....--...-.---_................................................ Shonkin stock ...................... ....-'---.--...--"..... Minor laccolith of the Shonkin Sag .._..-..-.............-..-.......... Major laccolith of the Shonkin...Shonkin Sag ................................... Ends of the laccolith wall............................ |  | | Journal (article/letter/editorial) | | Montana Mineral Locality Index Downloaded by [University of Nebraska, Lincoln] at 20:00 09 April 2015...2015 K NOWN AS THE TREASURE STATE, Montana is rich in mineral and gemstone localities. The state motto...The middle third of the state is known as the Montana alkali province where the sediments have MICHAEL...Indian Queen mine ca. 1905 at Farlin, Beaverhead County. 208 ROCKS & MINERALS Downloaded by [University... the Rocky Mountains, and furthest to the northwest, the belt basin. The Rocky Mountains contain sedimentary |  | | Journal (article/letter/editorial) | | of actinolite, opaque oxide minerals and dusty titanite. This alteration is greatest along grain boundaries...phases, whereas ill-defined aggregates of dusty titanite represent their non-pseudomorphous degradation...minerals." This has been documented in the Shonkin Sag Laccolith (Nash and Wilkinson, 1970), the Shiant Isles...model is simialr to that proposed for the Shonkin Sag Laccolith (Nash and Wilkinson, 1970) and Shiant Isles...to meta-igneous pyroxencs from the Adirondack Mountains, New York. Contrib. Mineral. Petrol., 97, 66-71 |  | | Journal (article/letter/editorial) | | feldspar, clinopyroxene, plagioclase, scapolite and titanite, with minor biotite and hornblende among elongated...magnetite, pyrite, quartz in trace amounts, anhedral titanite and euhedral zircon. Secondary minerals are limited...medium-grained amphibole, apatite, alkali feldspar and titanite, and fine-grained microcline and plagioclase.... Apatite, ilmenitc, magnetite and titanite are accessory. Titanite forms secondary rims around biotite...right), subrounded titanite (upper right), subhedral biotite and anhedral titanite rimmed by dark allanite |  | | Journal (article/letter/editorial) | | alkali-feldspar, aegirinic pyroxenes, plagioclase, titanite, apatite, natrolite and opaques. The order of...(diopside-salite, kaersutite, olivine, plagioclases, opaques, titanite, natrolite, alkali-feldspar, biotite) and minor...Nash and Wilkinson (1970), working on the Shonkin Sag laccolith, have shown that acmitic pyroxenes can crystallize... W. P., Wilkinson, J. F. G., 1970: Shonkin Sag Laccolith, Montana. I. Mafic minerals and estimates of |  | | Journal (article/letter/editorial) | | magnesianhedenbergite, with minor apatite and titanite, whereas the early assemblagein amygdule centers...overgrow early Occunnnxcn pyroxene, apatite, and titanite. Prehnite and calcite are Heat transfer associatedwith...amphibolite facies marbles in the Adirondack mountains of easternNew York (Valley et al., 1983).Valley...that include nepheline syenites in the Shonkin Sag laccolith, Montana (Nash and Wilkinson, 1970) and garnet-ijolite...zeolites, and nepheline at both localities. At Shonkin Sag, sanidine and arfvedsonite are part of the primary |  | | Journal (article/letter/editorial) | | clinopyroxene, nepheline and alkalifeldspar, with titanite, calcite and apatite as common accessory phases...defined by the accumulation of pyroxene and minor titanite. Near-monomineralic mafic layers have sharp basal...euhedral perthite ( l-8 mm) with accessory calcite, titanite, apatite, vesuvianite, disseminated graphite,...complexes are included for comparison. l=Shonkin Sag laccolith (Nash and Wilkinson, 1970), Z=Ilimaussaq... W.P. and Wilkinson, J.F.G., 1970. Shonkin Sag Laccolith, Montana. I. Matic minerals and estimates of |  | | Journal (article/letter/editorial) | | interstitial texture between large feldspars. Titanite, biotite and (±) clinopyroxene occur in minor...(Fig. 2e). Accessory minerals include apatite, titanite and opaque phases. Fig. 2 a) Large K-feldspar...the breakdown of titanian-bearing phases such as titanite and ilmenite under oxidizing conditions and low...S. 1942: Alkaline rocks of Iron Hill, Gunnison County, Colorado, US. – Geological Survey Professional...Nash, W.P., J.F.G. Wilkinson 1970: Shonkin Sag Laccolith, Montana. I. Mafic minerals and estimates of |  | | Journal (article/letter/editorial) | | – 3% Fe-Ti oxide and 0 – 3% sodalite. Apatite, titanite, eudialyte, a laÊ venite-like mineral and aenigmatite...1 –5% Fe-Ti oxide and 0 – 5% quartz. Apatite, titanite, aenigmatite, zircon, chevkinite-(Ce), pyrochlore...eudialyte, Lvn = laÊ venite-like mineral, Ttn = titanite, Ap = apatite, Ang = aenigmatite, Zrc = zircon...contains small inclusions of feldspar, apatite, titanite and Fe-Ti oxides. Quartz 754 Quartz occurs interstitially...syenite pegmatites from Gordon Butte, Crazy Mountains (Montana, USA). They suggested that leaching of Na from |  | | Journal (article/letter/editorial) | | titaniferous magnetite are altered and rimmed by titanite or by aenigmatite, which can also occur as large...phenomenon was observed in rocks from the Shonkin Sag laccolith (Montana) where the different trends are even...Nash, W.P. and Wilkinson J.F.G. (1970) Shonkin Sag laccolith, Montana. I: Mafic minerals and estimates of |  | | Journal (article/letter/editorial) | | ferrosalite join. A similar trend was observed in the Shonkin Sag sodic syenites FIG. 5. Plot of pyroxene compositions...ubiquitous presence of the assemblage magnetite + titanite + quartz in the TNUP suggests crystallization...the flanks of the Oligo-Miocene Rio Grande rift, USA: Monitors of the zone of lithospheric mantle extension...P., and Wilkinson, J. F. G., 1970, Shonkin Sag laccolith, Montana. Mafic minerals and estimates of temperature...Evidence from Miocene minettes of north west Colorado, USA: Earth Planet. Sci. Lett., v. 98, p. 139-153. Thompson |  | | Journal (article/letter/editorial) | | Weed and Pirsson (IX. p. 11), the ratio for the Shonkin Sag laccolite is not more than one-fortieth. On the...laccoliths from intrusive sheets; the most typical laccolith may be regarded as a very short, thick, domed...regarded as a very flat, thin laccolith. . . . Nevertheless, in the typical laccolith we presuppose a certain...products, magnetite and hydrous oxides of iron, titanite, epidote and zircon. Specific gravity of the most...between augite-syenite and shonkinite in the Shonkin Sag laccolite : I X . p. 8.) The transition rocks |  | | Journal (article/letter/editorial) | | a) two phases of deformation in the rocks, b) Titanite rims around ilmenite in the amphibolites, c) garnets...samples. Opaque minerals and titanite are other phases in the rocks. Titanite forms a rim around ilmenite...W. P. & Wilkinson, J. F. G. (1970): Shonkin Sag Laccolith, Montana. I. Mafic minerals and estimates of |  | | Journal (article/letter/editorial) | | and zircon are common accessories, whereas some titanite occurs in the medium-grained syenites. The plutonic...zircon are the main accessories, although some titanite occurs in the medium-grained syenites and oxides...ferro-ekermanite 3.1% Wo35En1Fs64 Wo1En0Fs99 Apatite and titanite 5.32% Mpd1 Fine-grained quartz syenite 13...increase of Na and Fe3+. Moreover, the presence of titanite in the medium-grained quartz syenites also indicates... W.P. and Wilkinson, J.F.G. (1970) Shonkin Sag laccolith, Montana. 1. Ma c minerals and estimates of |  | | Journal (article/letter/editorial) | | of eudialyte and steenstrupine and the lack of titanite are common to the two bo~ies. The detailed chemical... W. P. & Wilkinson, J. G. F. 1970: Shonkin Sag Laccolith, Montana. i. Mafi¢ minerals and estimates of |  | | Journal (article/letter/editorial) | | emplacement was the description of the Shonkin Sag laccolith in the United States of America by Pollard...the magmatic fingers associated with the Shonkin Sag laccolith and suggested that the crystallizing chill... Maas, R. and Gibson, R. (2001). Precise U-Pb titanite age constraints on the emplacement of the Bushveld |  | | Journal (article/letter/editorial) | | Mineral. Petrol. 50, 135-144 (1975) Morgante, S.: La titanite a terre rare del granito pegmatitico di Quoscescer...(1972) Nash, W.P., Wilkinson, J.F.G. : Shonkin Sag Laccolith, Montana. 1. Mafic minerals and estimates of |  | | Journal (article/letter/editorial) | | magnetite) Magnetite is rimmed by REE-rich titanite)an REErich titanite (Table 6) similar in composition to...in the more highly evolved rocks of the Shonkin Sag laccolith, M o n t a n a (Nash, 1972). Britholite-(Ce)...322 6,503 1.611 1,028 1.270 1.040 0,055 titanite 25(0) 24(0) Si P total ca La203 Ce203 Pr203...Bastnasite-(La) D Daqingshanite A Allanite-(Ce) T Titanite 0.5- " 0 ;2 4 6 8 1'0 1'2 1'4 1'6 ...minerals. The arrows against allanite, (Ce) (A) and titanite (T) indicate the Nd is below detection limit and |  | | Report (volume) | | ...................... 1. Rocks from Aroostook County..... ^..................'........... 2. Miscellaneous...1. Elliott County dike............................................... 2. Crittenden County dike..........................:........................ 70 Montana. ................................................ Crazy Mountains............................................... 80 5. Little Belt Mountains .-. .^..... 7. Highwood Mountains.... ....I.................................. 8. Little Rocky Mountains...... |  | | Report (issue) | | metamorphosed hydrothermal system at Pine Canyon. Piute County, Utah. U.S.A. [abs.]: Mineralogical Society (London)...buried, Precambrian features underlying Franklin Mountains and Great Bear and Mackenzie Plains: Bulletin...mineralogy of the Cerrillos copper deposit, Santa Fe County, New Mexico: New Mexico Geological Society Guidebook...Tectonics of the Jemez lineament in the Jemez Mountains and Rio Grande rift: Journal of Geophysical Research... E. E.. 1991. The igneous rocks of the Lincoln County porphyry belt, New Mexico: constraints on magma |  | | Journal (article/letter/editorial) | | crystals Kaersutite apatite and scarce bio- sphene (titanite) tite ilmenite + titano-magnetite – phenocrysts...Kaersutite and apatite occasional bio- sphene (titanite) tite ilmenite + rare titano-magnetite Peralkaline...porphyritic) Salite and aegirine biotite apatite titanite ilmenite + titano-magnetite Trachytes – abundant...Na2O: 12.29 wt.%) arfvedsonite biotite apatite titanite ilmenite + pseudobrookite, rare titano-magnetite...f.u.) apatite vol.% titano-magnetite apatite titanite Fe-Ti oxides apatite 5.32 vol.% XFe = 100 x |  | | Report (volume) | | crystalline rocks Maine 1. Rocks from Aroostook County 2. Litchtieldite and associated minerals New lIampshire...Carolina (ieorgia Kentucky 1. Elliott County (like 2. Crittenden County dike Tennessee Missouri Arkansas Texas...hsarokite-shoshonite-banakite series 5. M iscellaneous rocks Montana 1. Madison and Gallatin valleys 2. Butte district...4. Crazy Mountains 5. Little Belt Mountains 6. Castle Mountain district 7. Highwood Mountains 8. Little...Little Rock Mountains 9. Bearpaw Mountains 10. Elkhorn mining district 11. Bitterroot Range 12. Marysville |  | | Report (volume) | | crystalline rocks Maine 1. Rocks from Aroostook 'County 2. Miscellaneous rocks5 v New Hampshire 5 Vermont...Carolina Georgia Kentucky 1.. Elliott County dike 2. Crittenden County dike Tennessee Missouri Arkansas Oklahoma...Miscellaneous rocks 5 Montana 1. Madison and Gallatin valleys 2. Helena-Butte region 3. Crazy Mountains 4. Little...Belt Mountains5 5. Castle Mountain district 6. Highwood Mountains5 7. Bearpaw Mountains5 8. Elkhorn mining...Grande Canyon 5 2. Mount Taylor region 5 3. Colfax County 4. Miscellaneous rocks 5 Arizona 1. Globe district |  | | Book (edition) | | ; Spanish Peak, Colorado; and the Crazy Mts., Montana. Some dykes are composite, that is, they consist...intrusion which has been called a laccolith or stone-cistern. The ideal laccolith has the shape of a plano-convex...which the magma entered is in the floor of the laccolith, then the whole thing should have a rough resemblance...one. The essential point which differentiates a laccolith from an ordinary sill is the rapid increase in...of the laccoliths of the Henry Mountains is one to seven; in Shonkin Sag it is one to forty; in the average |  | | Audio (Series) | | 73—(OH)2Mg;S8isOi10: MgO—31.7; SiO.2—63.5; H,O—4.8 Titanite: 3.52—CaTiSiO;: CaO—28.6; TiO.—40.8; SiO, —31...several igneous rocks. Minute traces of zircon and titanite are more easily estimated from section than by...pow1 Prrsson, L. V., Igneous rocks of the Highwood Mountains, U. 8. Geol. Survey Bull. 237, p. 73, 1905...hornblende, 3 per cent; biotite, 2 per cent; accessory titanite, magnetite and apatite. The augite has a 1Cuapp...1Cuapp, C. H., Geology of the igneous rocks of Essex County, Mass., U. 8. Geol. Survey Bull. 704, 1921. 2 Buss |
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